Piano Fact

QUESTION: What exactly does it mean to modulate a song? Is it the same as changing the key? If not, whats the difference?

ANSWER: A modulation is a key change. All modulations are key changes, but not all key changes are modulations.

First we must differentiate between modulations in classical music versus modulations in popular music. In classical music a modulation is a temporary change of the pieces key. In early classical music pieces typically modulated up a fourth or a fifth, before returning to the original key. A good example would be a Bach fugue. Any Bach fugue. Its important to note that in classical music the decision to modulate is always made by the composer, not the performer.

In pop music its entirely different. Here, to modulate means to change the key of the song during the performance of it. And the decision to modulate is often in the hands of the performer or the arranger  rarely the composer.

Modulation is often used for a dramatic effect. Traditionally in pop music a performer may choose to modulate by raising the key a half step or a whole step. Technically the key change can go anywhere. But in practicality a dramatic modulation must go up not down (otherwise it wouldnt be dramatic) and it goes up just a minor or major second, not a fourth or fifth (otherwise youd be out of the vocal range of a singer).

Also in these situations, unlike in classical music, the modulation does not return to the original key. It either stays where it is, or it may modulate up again for more effect.

The best way to understand modulations is by noting various examples. One example of a single half-step modulation is found in Kenny Rogers TheGambler. You find a whole step modulation toward the end of Olivia Newton-Johns Let Me Be There.

The Bobby Darin recording of Mack the Knife modulates up a half step every single verse. Barry Manilow is known for multiple modulations as well.

Sometimes pop songs will modulate back and forth if there are a male and female vocalist trading verses. The excellent Verve album of Ella Fitzgerald and Louis Armstrong gives great examples.

The ability to modulate a song on ones own requires the pianist to have good skills in playing in all keys plus the knowledge of how to change from one key to another.

Do not confuse modulations with internal key changes. The Jerome Kern song All the Things You Are technically travels through at least five keys before ending in its original key. These key changes are designed by the composer  not the performer  and they are not permanent. The song eventually returns to the original key. As such we dont tend to refer to these temporary changes of the tonal center (or key) as modulations.